Semiconductor stress transducer

ABSTRACT

A semiconductor stress transducer having a pair of spaced electrodes disposed on an electrically insulating thin-film base of a flexible nature, a semiconductor piezo-resistive film being evaporated across the electrodes, means for applying an external stress to the evaporated semiconductor film so that a change in the external stress causes a change in the tension of the semiconductor film, and means for deriving an electrical signal from the electrodes due to a change in the internal resistance of the semiconductor film response to the change in the externally applied stress.

United States Patent Oda et al.

[ 1 June 27, 1972 [541 SEMICONDUCTOR STRESS TRANSDUCER [72] Inventors: Fujlo Odn, Ashiya; Shuiehi Obatn, Kyoto,

both of Japan Matsushlta Electric Industrlnl Co., Ltd., Osaka, Japan [22] Filed: Mayl, 1970 [21] Appl.No.: 34,505

[73] Assignee:

[30] Foreign Application Priority Date May 8,1969 Japan..................................44I36846 May 8, 1969 Japan... 44136847 May 8, 1969 Japan... 44/36848 May 8, 1969 Japan... 44/36849 May 8, 1969 Japan... 441361150 May 8, 1969 Japan... 44/36851 May 8, 1969 Japan... 44/36852 May 8, 1969 Japan... 44/136853 May 8, 1969 Japan... ...44/36854 May 8, 1969 Japan ..44/36855 [52] U.S.Cl. ..179/I00.41V, 179/l00.41 K, 179/110 B, 179/110 D, 338/2 [51] Int. 1/16, H04r 9/12, H04r 1 1/08 [58] Field of Search ..l79/l00.4l K, 100.41 V, 1108,

{56] Re'lereneea Cited UNITED STATES PATENTS FOREIGN PATENTS OR APPLICATIONS 1,155,519 6/1969 Great Britain ..l79/1I0 D Primary Examiner-Robert L. Griffin Assistant Examiner-Richard K. Eckert, Jr. AttorneyStevens, Davis, Miller & Mosher [S 7] ABSTRACT A semiconductor stress transducer having a pair of spaced electrodes disposed on an electrically insulating thin-film base of a flexible nature, a semiconductor piezo-resistive film being evaporated across the electrodes, means for applying an external stress to the evaporated semiconductor film so that a change in the external stress causes a change in the tension of the semiconductor film, and means for deriving an electrical signal from the electrodes due to a change in the internal resistance of the semiconductor film response to the change in the externally applied stress.

9 Claims, 35 Drawing Figures P'A'Tl-iminmzv m2 SHET 01 0F 12 FIG.

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SEMICONDUCTOR STRESS TRANSDUCER This invention relates to a semiconductor stress transducer in which the piezo-resistive effect of a semiconductor film evaporated on an electrically insulating film of flexible nature is utilized for the stress-electrical conversion, and also relates to a pickup cartridge employing such a transducer.

l-Ieretofore, various acoustic transducer elements utilizing the piezo-resistive effect of single crystals of silicon and germanium have been proposed and put into practical use. However, in order to obtain an effective sufficient conversion effect and a sufficiently large output voltage, it has been required that the acoustic transducer element be formed as a very small rod or thin strip having a cross-sectional area of less than 0.1 mm and such a rod or sheet be bonded to a mechanical vibrating system for the application of a uniaxial stress thereto.

The prior art transducer element employing the single crystal has had a very small mechanical compliance and therefore difficulties have been frequently encountered in the mechanical construction of a transducer possessing good acoustic properties. Further, semiconductor techniques of very high precision have been required in view of the requirement for very fine finish, and the element thus obtained has not had a sufiiciently high mechanical strength, which frequently leads to rejection during the assembling of the transducer.

It is therefore an object of the present invention to provide a semiconductor stress transducer which can be easily fabricated and has a good conversion effect by virtue of the fact that it comprises a semiconductor film evaporated on an electrically insulating film of flexible nature and utilizes the piezo-resistive effect of the evaporated film.

Another object of the present invention is to provide a pickup cartridge having a stresselectrical transducer element which utilizes the piezo-resistive effect of a semiconductor film evaporated on an electrically insulating thin-film base of a flexible nature.

The present invention provides a semiconductor stress transducer comprising a stress transducer element in the form of an evaporated thin-film semiconductor element including an electrically insulating thin-film base of a flexible nature, a pair of spaced electrodes disposed on said base, and a semiconductor piezo-resistive film evaporated across said electrodes, means for applying an external stress to said evaporated thin-film semiconductor element so that a change in the external stress can cause a change in the tension of said semiconductor piezo-resistive film, and means for deliving an electrical signal from said electrodes due to a change in the internal resistance of said semi-conductor piezo-resistive film responsive to the change in the externally applied stress.

The transducer according to the present invention has a very large compliance by virtue of the fact that the insulating base and the evaporated semiconductor film are very flexible, and thus shows an excellent conversion effect. Therefore, the transducer according to the present invention has improved properties over the prior art transducers of this kind employing the single crystals.

Further, the piezo-resistive element of any desired shape can be made in large quantities by suitably selecting the mask for evaporation because it is composed of an evaporated film. The piezo-resistive element has a sufficient flexibility and hence an adequately high mechanical strength. The semiconductor stress transducer of high utility thus obtained is best suited for use in microphones and pickup cartridges Several embodiments of the present invention will be described in detail with reference to the accompanying drawings, in which:

FIG. I is a sectional view of an evaporated thin-film semiconductor element constituting the transducing section of a transducer according to the present invention;

F IG. 2 is a schematic view showing the operating principle of a transducer employing the element shown in FIG. 1;

FIG. 3 is a schematic view of another embodiment of the transducer according to the present invention;

FIG. 4 is a perspective view of an embodiment of the pickup cartridge according to the present invention;

FIG. 5 is an axial sectional view of the shown in FIG. 4;

FIG. 6 is a perspective view of the internal mechanism of the pickup cartridge;

FIG. 7 is an exploded view of the internal mechanism shown in FIG. 6;

FIGS. and 8b are front elevational views of two forms of the mechano-electrical transducer section in the pickup cartridge;

FIG. 9 is a diagrammatic view showing the manner of operation of the pickup cartridge shown in FIGS. 4 and 5;

FIG. 10 is a perspective view of a modification of the internal mechanism shown in FIG. 6;

FIG. 11 is an axial sectional view of another embodiment of the pickup cartridge according to the present invention;

FIG. 12 is a perspective view of the internal mechanism of the pickup cartridge shown in FIG. I 1;

FIG. 13 is an exploded view of the internal mechanism shown in FIG. I2;

FIGS. 14a and 141: are front elevational views of two forms of the mechano-electrical transducer section in the pickup cartridge;

FIG. 15 is a diagrammatic view showing the manner of operation of the pickup cartridge shown in FIG. ll;

FIG. 16 is an axial sectional view of a further embodiment of the pickup cartridge according to the present invention;

FIG. 17 is a perspective view of the internal mechanism of the pickup cartridge shown in FIG. 16;

FIG. 18 is an exploded view of the internal mechanism shown in FIG. 17;

FIG. 19 is a front elevational view of the mechano-electrical transducer section in the pickup cartridge shown in FIG. I6;

FIG. 20 is a diagrammatic view showing the manner of operation of the pickup cartridge shown in FIG. 16;

FIG. 21 is a perspective view of the internal mechanism in a modification of the pickup cartridge shown in FIG. 16;

FIG. 22 is an exploded view of the internal mechanism shown in FIG. 21;

FIG. 23 is a front elevational view of the mechano-electrical transducer section in the pickup cartridge shown in FIG. 2l

FIG. 24 is a perspective view of the internal mechanism of a still further modification of the pickup cartridge shown in FIG. 16;

FIG. 25 is an axial sectional view of another embodiment of the pickup cartridge according to the present invention;

FIG. 26 is a perspective view of the internal mechanism of the pickup cartridge shown in FIG. 25, with certain parts removed;

FIG. 27 is an exploded view of the internal mechanism shown in FIG. 26;

FIG. 28 is a diagrammatic view showing the manner of operation of the pickup cartridge shown in FIG. 25;

FIG. 29 is a perspective view of the internal mechanism of still another embodiment of the pickup cartridge according to the present invention;

FIG. 30 is an axial sectional view of the internal mechanism shown in FIG. 29;

FIG. 31 is an exploded view of the internal mechanism shown in FIG. 29;

FIG. 32 is a diagrammatic view showing the manner of operation of the pickup cartridge shown in FIG. 29; and

FIG. 33 is a partly broken-away perspective view of a microphone employing the transducer according to the present invention.

Referring first to FIG. 1 showing one form of an evaporated thin-film semiconductor element, a base I is in the form of a thin-film of electrically insulating material such as polyimide, polyamide or mica about several 10 microns thick which has a sufficiently high heat resistance to heat and which possesses very high flexibility. A pair of spaced electrodes 2 and 2' are deposited adjacent to opposite ends of the base 1 by evaporating under vacuum a metal such as nickel. chromium or gold. A

pickup cartridge semiconductive material showing a high piezo-resistive effect such as silicon, germanium or indium antimony doped with a suitable impurity is evaporated in strip form by the use of a suitable evaporation mask so as to provide a piezo-resistive film 3 which extends across these two electrodes 2 and 2'. Thus, when the piezo-resistive film 3 is subject to a change in the tension in a direction of the line connecting the electrodes 2 and 2 and when the film 3 is deformed by a bending stress applied thereto, the mechanical strain occurring therein causes a change in the resistance across the electrodes 2 and 2'.

FIG. 2 shows schematically the operating principle of a stress transducer employing such an evaporated thin-film semiconductor element. A block 4 of electrically insulating material fixedly supports the evaporated thin-film semiconductor element and is formed with a central recess 5 so that the piezo-resistive film 3 in the evaporated thin-film semiconductor element lies over the recess 5 and the electrodes 2 and 2 are securely fixed on the upper edge portions of the recess 5. By this arrangement, the piezo-resistive film 3 is continuously maintained under a constant tension. The tension is not especially great and is such that no wrinkles or drooping occurs on the film portion.

The piezo resistive film 3 is subject to a change in the tension in a direction parallel to the film surface as shown by the arrows 8 and 8' when a member 6 engaging the center of the evaporated thin-film semiconductor element applies vibrations to the element in a direction as shown by the arrow 7. The change in the tension causes at the same time a mechanical deformation in the central portion of the film.

When thus the piezo-resistive film 3 is subject to both the change in the tension and the mechanical deformation, a change in the resistance, which is proportional to the vibrations stress applied by the member 6 occurs in the piezoresistive film 3 and this change in the resistance is converted into a corresponding change in the voltage across a load resistor 10 disposed in a closed circuit including a battery or DC. power supply 9, the load resistor 10 and the piezo-resistive film 3. The A.C. component is supplied through a capacitor 11 to a suitable external amplifier to be converted into acoustic ener' ln such a stress-electrical transducer system, the dynamic structure of the system is completely reversible. Therefore, the system applying the stress may be as shown in FIG. 3 in which the block 4 fixedly supporting thereon the piezo-resistive film 3 is movable in response to external force, while the member 6 engaging the central portion of the film 3 is fixed.

The practical structure of a pickup cartridge according to the present invention adapted for use with a stereophonic player will be described in detail with reference to FIGS. 4 through 9.

Referring to the drawings, a stylus l2 traces the sound grove ofa record disk to detect vibrations, and a cantilever 13 made from a light alloy material transmits the vibrations detected by the stylus 12 to a stress transducer section. A fine wire 14 of very small diameter functions as a supporting point for the stylus l2 and the cantilever l3 vibrating while tracing the sound groove and is fixedly supported at one end in the inner end of the cantilever 13 through a spacer 15. A support 16 fixed adjustably the fine wire 14 to the cartridge body and is secured while being spaced from the inner end of the cantilever 13 a slight distance of less than 1 mm so that the stylus 12 and the cantilever 13 can make free vibrating movement by means of the fine wire 14.

A member 17 having four projections 18, 19, 20 and 21 extending in cross-like form therefrom is provided to apply pressure to an evaporated thin-film semiconductor element to cause a change in the resistance. The projections 18, 19, 20 and 21 are provided at their tips with abutments 22, 23, 24 and 25 having a conically finished smooth engaging surface, respectively. The inner end portion of the cantilever 13 is inserted and fixed in a central opening 26 of the member [7 so that, in this position, the projections 18, 19, 20 and 21 of the member 1') cross at right angles with respect to the axis of the cantilever 13 so that the vibrations transmitted from the stylus 12 can be divided and transmitted in the four directions.

A damper and support 27 serves to damp the resonance of the assembly including the stylus 12, the cantilever 13 and the member 17, and at the same time, to support the assembly on an electrically insulating block which will be described later. An electrically insulating base 28 in the form of a thin-film of electrically insulating material of flexible nature is similar to the insulating base 1 shown in FIGS. 1 and 2. This insulating base 28 has, for example, a substantially square shape as shown in FIG. 8a. The sides of the insulating base 28 are several millimeters long, and a central opening 29 is provided in the base 28. Semiconductor piezo-resistive films 30, 31, 32 and 33 are evaporated on the band-like portion defined between the sides and the edges of the opening 29 of the base 28, and electrodes 34, 34'; 35, 35'; 36, 36'; and 37, 37' are deposited to underlie the opposite ends of the respective piezo-resistive films 30, 31, 32 and 33.

The evaporated thin-film semiconductor element may be as shown in FIG. 8b in which it will be seen that recesses 38, 39, 40 and 41 are formed in the respective sides of the insulating base 28 so as to cause a greater change in the resistance of the semiconductor piezo-resistive films 30, 31, 32 and 33 in response to tension applied thereto. Strips 42, 43, 44 and 45 extend integrally from the four corners of the insulating base 28 in a direction opposite to the piezo-resistive films 30, 31, 32 and 33, and the electrodes 34, 34'; 35, 35", 36, 36'; 37 and 37' are extended along the respective strips 42, 43, 44 and 45 to the ends of the latter. The piezo-resistive films 30, 31, 32 and 33 are engaged by the respective abutments 22, 23, 24 and 25 of the member 17 to receive pressure therefrom.

An electrically insulating block 46 is formed with a crossshaped recess 47 on one surface thereof to receive thereon the insulating base 28 in such a manner that the piezo-rcsistive films 30, 31, 32 and 33 disposed on the insulating base 28 are positioned above the recess 47 so that a sufficient change in the tension can be produced when the piezo-resistive films 30, 31, 32 and 33 are pressed by the respective abutments 22, 23, 24 and 25 of the member 17. The support 16 is inserted at one end into a central opening 48 of the insulating block 46 and is fixed in place by a screw 49 after having been adjusted so that the abutments 22, 23, 24 and 25 of the member 17 apply a suitable pressure to the respective piezo-resistive films 30, 31, 32 and 33. In lieu offixing the support 16 by the screw 49, any other means such as a bonding agent may be employed. Terminals 50 are connected to the electrodes 34, 34", 35, 35'; 36, 36'; and 37, 37' for externally leading out the signal. A terminal plate 52 of an electrically insulating material supports the terminals 50, and the entire internal mechanism is housed in a cartridge casing composed ofa front section 53, an inter mediate section 54 and a rear section 55.

Operation of the pickup cartridge according to the present invention having a structure as described above will be given with reference to FIG. 9. FIG. 9 is a simplified diagram of the pickup cartridge and like reference numerals are used therein to denote like parts appearing in FIGS. 4 through 8. When now the stylus 12 is moved by a vibration in a direction shown by the arrow 56, the cantilever 13 is swung in a direction of the arrow 56 about a supporting point 57 provided by the front end of the fine wire 14. Thus, the abutments 23 and 25 of the member 17 swing about the supporting point 57 in direction shown by the arrows 58 and 59.

Due to the swinging movement of the abutments 23 and 25, the abutment 23 applies pressure to the piezo-resistive film 31 while the abutment 25 is moved away from the piezo-resistive film 33 to relieve the pressure. In this case, the abutments 22 and 24 swing in the directions shown by the arrows 60 and 61 about an axis shown by the dotted line and thus do not contribute to a change in the resistance of the piezo-resistive films 30 and 32. The above description has referred to the case in which the stylus 12 vibrates in the direction of the arrow 56.

When, however, the stylus 12 swings in a direction perpendicular to the direction 56, the piezo-resistive films 30 and 32 are applied with pressure thereby to generate a signal, while on the other hand, no change in the resistance occurs in the piezo-resistive films 31 and 33. In this manner, the stereophonic vibrations are separated in two channels for detection.

FIG. shows a modification of the pickup cartridge described above. This embodiment differs from the preceding embodiment in that rods 62, 63, 64 and 65 (the rod 62 is not shown) project in cruciform fashion from the member 17 so that they directly engage with the piezo-resistive films 30, 31, 32 and 33 with their side faces. The operation of this embodiment is similar to that of the preceding embodiment and the stereophonic vibrations transmitted through the stylus 12 are separated in two channels to thereafter be detected.

Another embodiment of the pickup cartridge according to the present invention adapted for use with a stereophonic player will be described with reference to FIGS. 11 through 15. A stylus 112 traces the sound groove of a record disk to detect vibrations, and a cantilever 113 made from a light alloy material transmits the vibrations detected by the stylus 112 to a stress transducer section. A support 114 of viscoelastic material functions as a supporting point for the stylus 112 and the cantilever 113 which vibrate while tracing the sound grove and is provided with a central opening 115 and a flanged portion 116 to serve as a supporting means for a crucial member 117 in the form of a fiat plate of metal or resin material having a central opening 118 and four projections or arms 119, 120, 121 and 122 lying in the same plane, while making substan tially right angles to each other.

An annular member or push ring 123 of a visco-elastic material has a central opening 124 for receiving therein the rear end remote from the flanged front end of the support 114. The cantilever 113 is inserted at one end into the opening 115 of the support 114 which is inserted through the opening 118 of the member 117 into the opening 124 of the ring 123 so that the member 117 can be supported between the ring 123 and the flanged portion 116 of the support 114. The ring 123 serves also as a damper for inhibiting the resonance of the above assembly. When the member 117 is so supported, the arms 119, 120, 121 and 122 of the member 117 lie substantially in a plane perpendicular to the axis of the cantilever 113. The rear end of the support 114 is passed through the ring 123 to be inserted into and fixed in place in a tubular member 125 for holding the vibrator including the stylus 112 and the cantilever 113 in the cartridge body.

An electrically insulating base 126 in the form ofa thin film of electrically insulating material ofa flexible nature is similar to the insulating base 1 shown in FIGS. 1 and 2. This insulating base 126 has, for example, a substantially square shape as shown in FIG. 14a. The sides of the insulating base 126 are several millimeters long, and a central opening 127 is provided in the base 126. Semiconductor piezo-resistive films 131 and 132 are evaporated respectively on a band-like portion 129 and an adjacent band-like portion 130 crossing at right angles to the band-like portion 129 defined between the sides and the edges of the opening 127 of the base 126, and electrodes 133, 133'; and 134, 134 are disposed to underlie the opposite ends of the respective piezo-resistive films 131 and 132. The insulating base 126 is provided with an auxiliary electrode 135 for connection to an auxiliary terminal during mounting of the base 126 in the cartridge. The evaporated thin-film semiconductor element may be as shown in FIG. 14b from which it will be seen that recesses 136, 137, 138 and 139 are fonned in the respective sides of the insulating base 126 so as to cause a greater change in the resistance of the piezo-resistive films 131 and 132 in response to the application of tension thereto. Further, in the element shown in FIG. 14b, the auxiliary electrutlc 135 is split into halves to be connected with the respective electrodes 133 and 134.

A cylindrical insulating block 140 of electrically insulating material has 11 central opening 141 and is provided with three projections 145, 146 and 147 on one face thereof. The pro jections 145, !146 and 147 are integral with respective terminal rods 142, 143 and 144, the projection 146 being split into two semicircular projections 146' and 146", and the terminal rod 143 being also split into two independent terminal rods 143' and 143". An auxiliary projection 148 of the same shape as the projections 145, 146 and 147 is disposed at such a position on the face of the cylindrical block 140 that it occupies a comer of the square constituted by the projections 145, 146 and 147 plus the projection 148.

The ring 123 and the tubular member are inserted into the opening 127 of the insulating base 126 until the arms or abutments 119, 120, 121 and 122 of the member 117 engage the face of the base 126 opposite to the face carrying the piezo-resistive films 129 and 130, and then the ring 123 and the tubular member 125 are inserted into the central opening 141 of the insulating block to fix the assembly into place. The tubular member 125 is so fixed in the insulating block 140, that the member 117 is brought into contact with the insulating base 126 with a slight pressure by being forced by the support 114. The electrodes 133 and 133' for the piezo-resistive film 129 are electrically and mechanically fixed to the respective projections 145 and 146' of the block 140, the electrodes 134 and 134' for the piezo-resistive film 130 are likewise fixed to the respective projections 147 and 146". The auxiliary electrode 135 is also fixed with the auxiliary projection 148, and the piezo-resistive films 129 and 130 are disposed between the projections 145, 146 and 147, respectively.

By the above structure and combination, stereophonic vibrations detected by the stylus 112 are transmitted to the member 117 and separated into horizontal and vertical vibrations by means of the abutments 119, 120, 121 and 122, the vibrations being applied to the insulating base 126 to cause a change in the tension of the piezo-resistive films 129 and 130 so that a change in the internal resistance of the piezo-resistive films 129 and 130 corresponding to a change in the tension can be derived from the terminal rods 142, 143 and 144.

Operation of the pickup cartridge shown in FIGS. 11 through 14 will be described with reference to FIG. 15 which is a simplified diagram of the pickup cartridge and in which like reference numerals are used to denote like parts appearing in FIGS. 11 through 14. When new the stylus 112 is moved by a vibration in a direction of the arrow 149, the cantilever 113 is swung in a direction of the arrow 149 about a supporting point 150 Thus, the abutments 120 and 122 of the member 117 swing about the supporting point 150 in directions shown by the arrows 151 and 152. The swinging movement of the abutments 120 and 122 in the directions of the arrows 151 and 152 applies pressure to the piezo-resistive film 131. In this case, the abutments 119 and 121 of the member 117 swing in directions shown by the arrows 153 and 154 about an axis shown by the dotted line, and thus the abutment 121 applies no pressure to the piezo-resistive film 132 and does not contribute to any change in the internal resistance of the piezo-resistive film 132. Due to the pressure applied to the piezo-resistive film 131 by the abutment 120, a change occurs in the internal resistance of the piezo-resistive film 131 and is detected.

The above description has referred to the case in which the stylus 112 vibrates in the direction of the arrow 149. When, however, the stylus 112 vibrates in a direction perpendicular to the direction 149, the abutment 121 of the member 117 now applies pressure to the piezo-resistive film 132, while no pressure is applied to the other piezo-resistive film 131. In this manner, the stereophonic vibrations are separated into two channels.

A further embodiment of the pickup cartridge according to the present invention adapted for use with a stereophonic player will be described with reference to FIGS. 16 through 24. A stylus 212 traces the sound groove of a record disk to detect vibrations, and a cantilever 213 made from a light alloy material transmits the vibrations detected by the stylus 212 to a stress transducer section. A fine wire 214 having a very small diameter functions as a supporting point for the stylus 212 and the cantilever 213 which vibrate while tracing the sound groove and the wire is fixedly supported at one end in the inner end of the cantilever 213 through a spacer 215. A support 216 attaches adjustably the fine wire 214 to the cartridge body and is fixed while being spaced from the inner end of the cantilever 213 at a small distance of less than 1 mm so that the stylus 212 and the cantilever 213 can make a free vibratory movement by means of the fine wire 214.

A member 217 having two projections 218 and 219 arranged in a V-Iike formation lying in the same plane while making substantially right angles with respect to each other is provided in order to apply pressure to an evaporated thin-film semiconductor element constituting the mechano-electrical transducer section. The projections 218 and 219 are provided at their tips with abutments 220 and 221 having a conically finished smooth engaging surface, respectively. The inner end of the cantilever 213 is inserted and fixed in a central opening 222 of the member 117 having the integral projections 218 and 219 so that the stereophonic vibrations transmitted through the stylus 212 can be transmitted to the individual projections 218 and 219 arranged in the V-formation.

A damper and support 223 serves to damp the resonance of the assembly including the stylus 212, the cantilever 213 and the member 217, and at the same time, to support the assembly on an electrically insulating block which will be described later. An electrically insulating base 224 in the form of a thin film of electrically insulating material of flexible nature is similar to the insulating base 1 shown in FIGS. 1 and 2. The insulating base 224 has, for example, a shape as seen in FIG. 19 and is substantially in the form of V including five portions, 225, 226, 227, 228 and 229. Semiconductor piezo-resistive films 230 and 230' are evaporated on the respective portions 226 and 228 under the same conditions as those described with reference to FIGS. 1 and 2 so that the lines extending in the longitudinal direction of the films cross at right angles to each other. The portions 225 and 227 are provided with respective electrodes 231 and 231' for the piezo-resistive film 230, while the portions 227 and 229 are provided with respective electrodes 232 and 232 for the piezo-resistive film 230'. The outer sides of the portions 226 and 228 are formed with recesses 233 and 234 so as to augment a change in the resistance due to a change in the tension of the piezo-resistive films 230 and 230.

Strips 235, 236 and 237 extend integrally from the portions 225, 227 and 229 of the insulating base 224 in a direction opposite to the piezo-resistive films 230 and 230', and the electrodes 231, 231, 232 and 232' are extended along these strips 235, 236 and 237 to the ends of the latter. The piezo-resistive films 230 and 230' are engaged by the respective abutments 220 and 221 of the member 217 to receive pressure therefrom.

An insulating block 238 is provided with a central opening 239 and a pair of recesses 240 and 241 extending in a V-like fashion from the central opening 239. The insulating base 224 fits on the insulating block 238 so that the piezo-resistive films 230 and 230' deposited on the insulating base 224 are disposed above the respective recesses 240 and 241 and a sufficient change in the tension can be obtained when the piezoresistive films 230 and 230' are pressed by the respective abutmems 220 and 221 of the member 217.

The support 216 is inserted at one end through the ring 223 into the central opening 239 of the insulating block 238 and is fixed in place by a screw 242 after being adjusted so that the abutments 220 and 221 apply a suitable pressure to the respective piezo-resistive films 230 and 230'. In lieu of fixing the support 216 by the screw 242, any other means such as a bonding agent may be employed. Terminals 243 are connected to the electrodes 231, 231'; and 232, 232 for externally leading out the signal. A terminal plate 244 of electrically insulating material supports the terminals 243, and the entire internal mechanism is housed in a cartridge casing composed of sections 245 and 246.

Operation of the pickup cartridge according to the present invention having a structure as shown in FIGS. 16 through 19 will be described with reference to FIG. 20 which is a simplified diagram of the pickup cartridge and in which like reference numerals are used to denote like parts appearing in FIGS. 16 through 19. When now the stylus 212 is moved in a direction shown by the arrow 247, the cantilever 213 is swung in a direction of the arrow 247 about a supporting point 248 provided by the front end of the fine wire 214. Thus, the abut ment 220 of the member 217 swings about the supporting point 248 in a direction shown by the arrow 249. Due to the swinging movement of the abutment 220 in the direction of the arrow 249, the abutment 220 applies pressure to the piezoresistive film 230. In this case, the abutment 221 of the member 217 swings in a direction shown by the arrow 250 about an axis shown by the dotted line and thus does not contribute to a change in the resistance of the piezo-resistive film 230'. The above description has referred to the case in which the stylus 212 vibrates in the direction of the arrow 247. When, however, the stylus 212 swings in a direction perpendicular to the direction 247, the abutment 221 now applies pressure to the piezo-resistive film 230' to cause a change in the resistance of the latter, while no change in the resistance occurs in the piezo-resistive film 230. In this manner, the stereophonic vibrations are separated in two channels to be detected.

FIGS. 21, 22 and 23 show a modification of the pickup cartridge shown in FIGS. 16 through 19. In this modification, the insulating base 224 includes a pair of arms 252 and 253 extending in a V-formation integrally from an annular member 251. The piezo-resistive films 230 and 230' are evaporated on the respective arms 252 and 253. A central projection 254 extends integrally from the outer periphery of the annular member 251 at a position intermediate between the arms 252 and 253. An electrode 255 common to the piezo-resistive films 230 and 230' is deposited adjacent to the central projec tion 254, and the arms 252 and 253 are bent to provide respective extensions 256 and 257 along which electrodes 258 and 259 for the respective piezo-resistive films 230 and 230' are extended. The insulating block 238 in this modification is in the form of a cylinder having a diameter substantially the same as that of the annular member 251 and has a pair of projections or ridges 260 and 261 extending integrally therefrom at right angles with respect to each other. The ridges 260 and 261 are formed with respective recesses 262 and 263 at the end opposite to the annular member 251.

The structure of this embodiment is such that the annular member 251 is bonded to the face of the insulating base 224, and the piezo-resistive films 230 and 230' register with the recesses 262 and 263 of the respective ridges 260 and 261, the extensions or bent portions 256 and 257 of the respective arms 252 and 253 being bonded to the longitudinal faces of the respective ridges 260 and 261, and the projection 254 being bonded to a portion of the peripheral face of the insulating block 238. Thus, this embodiment is featured by the fact that the internal mechanism is quite small in size.

FIG. 24 shows a further modification of the pickup cartridge shown in FIGS. 16 through 19. In this modification, the member 217 has a pair of rods 264 and 265 projecting integrally therefrom in a V-formation. Three terminal rods 269, 270 and 271 having respective bent front end portions 266, 267 and 268 are fixed in corresponding recesses formed in the outer peripheral face of the insulating block 238 in such a manner that the bent end portions 266, 267 and 268 project from the front end face of the insulating block 238. Electrodes 231, 272 and 232 deposited on the insulating base 224 are bonded to the respective bent end portions 266, 267 and 268 of the terminal rods 269, 270 and 271 so that the piezo-resistive films 230 and 230' are disposed between the electrodes 231 and 272', and the electrodes 272 and 232, respectively. The rods 264 and 265 extending from the member 217 are brought into engagement at their side faces with the respective piezo-resistive films 230 and 230'. The operation of this em bodiment is similar to that of the preceeding embodiments so that the stereophonic vibrations detected by the stylus 212 can be separated into two channels.

Another embodiment of the pickup cartridge according to the present invention adapted for use with a stereophonic player will be described with reference to FIGS. 25 through 28.

A stylus 312 traces the sound groove of a record disk to detect the vibrations and a cantilever 313 made from a light alloy material transmits the vibrations detected by the stylus 312 to a mechano-electrical transducer section. A fine wire 314 of very small diameter functions as a supporting point for the stylus 312 and the cantilever 313 vibrating while tracing the sound groove and is fixedly supported at one end in the inner end of the cantilever 313 through a spacer 315. A support 316 fixes adjustably the fine wire 314 to the cartridge body and is fixed while being spaced from the inner end of the cantilever 313 a slight distance of less than 1 mm so that the stylus 312 and the cantilever 313 can make free vibrating movement by means of the fine wire 314.

A circular pressure applying member 317 is provided with a cylindrical abutment 318 for applying pressure to the evaporated thin-film semiconductor elements described later so as to cause a change in the resistance therein. The circular pressure applying member 317 is provided with a central opening 319 for fixedly receiving therein the inner end of the cantilever 313 in such a state that the member 317 is assembled with the cantilever 313 with the plane of the former crossing at right angles with the axis of the latter. A damper and support 320 is fitted on the rear end of the support 316 and engages the member 317 so that it serves to damp the resonance of the assembly including the stylus 312, the cantilever 313 and the circular pressure applying member 317, and at the same time, to support the assembly on an insulating block which will be described later.

Electrically insulating bases 321 and 322 in the form of a thin film of electrically insulating material of flexible nature are similar to the insulating base 1 shown in FIGS. 1 and 2. These insulating bases 321 and 322 are provided with respective central openings 323 and 324, and semiconductor piezoresistive films 325, 326, 327 and 328 are evaporated on opposite sides of the central openings 323 and 324 under the same conditions as those described with reference to FlGS. 1 and 2. Electrodes 329, 329; 330, 330'; 331, 331'; and 332, 332' are deposited at opposite ends of the respective piezo-resistive films 325, 326, 327 and 328. Strips 333, 333', 334, 334, 335, 335', 336 and 336' extend integrally at right angles from the sides adjacent to the respective electrodes 329, 329', 330, 330', 331, 331 332 and 332 on the insulating bases 321 and 322, and the electrodes 329 to 332 are extended along these strips 333 to 336 so as to easily provide for external connection, The two evaporated thin-film semiconductor elements having such a structure are assembled preferably in a crucial form with their central openings 323 and 324 registering with each other. In lieu of the above assembly, an insulating base of cruciate shape may be prepared and semiconductor piezo-resistive films may be evaporated thereon.

An insulating block 337 of crucial shape is provided with a central opening 338 and four recesses 339, 340, 341 and 342 at the center of the front face of the four arms crossing at right angles with the central axis. The evaporated thin-film semiconductor elements assembled in the crucial form are bonded to the front faces of the arms of the insulating block 337 having the recesses 339, 340, 341 and 342. The strips 333 to 336 are bonded to the side faces of the arms of the insulating block 337, and the support 316 supporting the circular pressure applying member 317 is inserted through the central openings 323 and 324 of the insulating bases 321 and 322 into the central opening 338 of the insulating block 337 and is fixed therein by a bonding agent or the like so that the end face of the abutment 318 of the circular pressure applying member 317 applies slight pressure to the piezo-resistive films 325, 326, 327 and 328. When the evaporated thin-film semiconductor elements are thus bonded to the insulating l 0 block 337, the piezo-resistive films 325, 326, 327 and 328 register with the respective recesses 339, 340, 341 and 342. The electrodes for the respective piezo-resistive films 325, 326, 327 and 328 are connected to terminals 344 and 345 fixed to a terminal plate 343. The entire internal mechanism is housed in a cartridge casing composed of sections 346 and 347.

Operation of the pickup cartridge of the present invention having a structure as described with reference to FIGS, 25 through 27 will be described with reference to FIG. 28 which is a simplified diagram of the pickup cartridge and in which like reference numerals are used to denote like parts appearing in FIGS. 25 through 27. When the stylus 312 is moved in a direction shown by the arrow 348, the cantilever 313 is swung in a direction of the arrow 348 about a supporting point 349 provided by the front end of the fine wire 314. Thus, pressure is applied to the circular pressure applying member 317 which in turn applied pressure to the piezo-resistive film 325 by the abutment 318 which is urged in a direction of the arrow 350, while pressure applied to the piezo-resistive film 326 is relieved as the corresponding portion of the abutment 318 is urged in a direction of the arrow 351. Due to the fact that the piezo-resistive film 325 is pressed and the piezo-resistive film 326 is relieved from the pressure, a change in the resistance occurs in the piezo-resistive films 325 and 326 and is detected. in this case, no change in the resistance occurs in the remaining piezo-resistive films 327 and 328 since those portions of the abutment 318 of the circular pressure applying member 317 contacting the piezo-resistive films 327 and 328 swing merely in directions shown by the arrows 352 and 353 about an axis shown by the dotted line.

When the stylus 312 swings in a direction perpendicular to the direction of the arrow 348, the piezo-resistive films 327 and 328 are now subject to application and relieving of pressure so that a change in the resistance occurs therein, while no change in the resistance occurs in the piezo-resistive films 325 and 326. In this manner, the stereophonic vibrations can be separated in two channels to be detected.

While this embodiment has referred to the provision of four semiconductor piezo-resistive films, two piezo-resistive films disposed adjacent to each other may merely be provided instead of four.

A further embodiment of the pickup cartridge according to the present invention adapted for use with a stereophonic player will be described with reference to F [GS 29 through 32.

A stylus 412 traces the sound groove of a record disk to detect the vibrations, and a cantilever 413 made from a light alloy material transmits the vibrations detected by the stylus 412 to a mechano-electrical transducer section. A fine wire 414 of very small diameter functions as a supporting point for the stylus 412 and the cantilever 413 vibrating while tracing the sound groove and is fixedly supported at one end in the inner end of the cantilever 413 through a spacer 415. A support 416 fixes adjustably the fine wire 414 to the cartridge body and is fixed while being spaced from the inner end of the cantilever 413 a slight distance of less than 1 mm so that the stylus 412 and the cantilever 413 can make free vibratory movements by means of the fine wire 414.

A member 417 having two projections 418 and 419 arranged in a V-like fashion lying in the same plane while making substantially right angles with respect to each other is pr0- vided to apply pressure to evaporated thin-film semiconductor elements constituting the mechano-electrical transducer section. The projections 418 and 419 are provided at their tips with abutments 420 and 421 having a conically finished smooth engaging surface, respectively. The inner end of the cantilever 413 is inserted and fixed in a central opening 422 of the member 417 having the integral projections 418 and 419 so that the stereophonic vibrations transmitted through the stylus 412 can be transmitted to the individual projections 418 and 419 arranged in the V-like fashion.

A damper and support 423 serves to damp the resonance of the assembly including the stylus 412, the cantilever 413 and the member 417, and at the same time, to support the assembly on an insulating block which will be described later. Electrically insulating bases 424 and 425 in the form of a thin film of electrically insulating material of flexible nature are similar to the insulating base 1 shown in FIGS. 1 and 2. Semiconductor piezo-resistive films 426 and 427, and electrodes 428, 428', 429 and 429' for the films are formed on these insulating bases 424 and 425 under the same conditions as those described with reference to FIGS. 1 and 2. Recesses 430 and 431 are formed on opposite longitudinal side edges of the insulating bases 424 and 425 so as to augment a change in the resistance of the piezo-resistive films 426 and 427 due to a change in the tension applied thereto.

An electrically insulating block 432 has the shape of a square block. In the upper and lower faces of the insulating block 432, there are fixed four terminal rods 437, 438, 439 and 440 having respective inwardly bent portions 433, 434, 435 and 436 at one end thereof. The electrodes 428, 428', 429 and 429' for the piezo-resistive films 426 and 427 evaporated on the respective insulating bases 424 and 425 are bonded to the bent end portions 433, 434, 435 and 436 of the respective terminal rods 437, 438, 439 and 440, and the piezo-resistive films 426 and 427 are situated between the bent end portions 433 and 434, and the bent end portions 435 and 436, rrespectively. The support 416 is inserted through the ring 423 into an opening 441 of the insulating block 432 and is fixed in place by means such as a bonding agent so that the abutments 420 and 421 of the member 417 apply a slight pressure to the respective piezo-resistive films 426 and 427 of the evaporated thin-film semiconductor elements.

Operation of the pickup cartridge of the present invention having a structure as shown in FIGS. 29 through 31 will be described with reference to FIG. 32 which is a simplified diagram of the pickup cartridge and in which like reference numerals are used to denote like parts appearing in FIGS. 29 through 31.

When now the stylus 412 is moved in a direction shown by the arrow 442, the cantilever 413 swings in a direction of the arrow 442 about a supporting point 443 provided by the front end of the fine wire 414. Thus, the abutment 420 of the member 417 swings in a direction of the arrow 444 about the supporting point 443. This swinging movement of the abutment 420 applies pressure to the piezo-resistive film 426 so that a change in the resistance responsive to the pressure is detected across the terminal rods 437 and 438. In this case, the abutment 421 of the member 417 makes a swinging movement in a direction shown by the arrow 445 about an axis shown by the dotted line and thus does not contribute to a change in the resistance of the piezo-resistive film 427. when, on the other hand, the stylus 412 swings in a direction opposite to the arrow 442, the pressure applied to the piezo-resistive film 426 is relieved, also resulting in a change in the resistance.

When the stylus 412 is moved in a direction perpendicular to the direction shown by the arrow 442, the piezo-resistive film 427 associated with the abutment 421 is now subject to application or relieving of pressure resulting in a change in the internal resistance of the piezo-resistive film 427. In this case, the abutment 420 merely swings about an axis, and no change in the resistance occurs in the piezo-resistive film 426. In this manner, the stereophonic vibrations are separated into two channels to be detected.

A microphone employing a stress transducer as shown in FIG. 1 is shown in FIG. 33. The microphone includes an evaporated thin-film semiconductor element comprising an insulating base 501, a pair of spaced electrodes 502 and 502', and a semiconductor piezo-resistive film 503 all of which are similar to those shown in FIG. 1. An insulating block 504 has a central circular recess 505 across which the evaporated thinfilm semiconductor element is bridged, and the element is securely fixed to the insulating block 504 at the electrodes 502 and 502'.

External terminals 512 and 513 connected to the respective electrodes 502 and 502' are connected to a suitable D.C. load circuit. A conventional diaphragm 514 is supported at its peripheral edge portion with pleats so as to increase the compliance and is integrally secured to a casing 515 together with the evaporated thin-film semiconductor element. At the center of the diaphragm 514, there is provided a member 506 for applying to the piezo-resistive film 503 a stress produced by acoustic energy. The tip of the member 506 has a width substantially equal to the width of the substrate 501 and is finished to a smooth surface. The tip of the member 506 need not be especially sharpened.

In the microphone employing the evaporated thin-film semiconductor element, stress is applied to the piezo-resistive film 503 of the evaporated thin-film semiconductor element by the vibrating movement of the diaphragm 514 and is converted into an electrical signal by the principle shown in FIG. 2.

What is claimed is:

l. A pick-up cartridge, comprising:

a cantilever;

a stylus mounted on one end of said cantilever;

a support member supporting said cantilever at its other end;

a substantially squareshaped flexible insulating film base, having a central opening and four band-shaped portions defined between the sides of said insulating film and said central opening, connected to said support member;

four band-shaped semiconductor piezo-resistive elements. each having electrodes at its opposite ends and mounted respectively on said four band-shaped portions of said insulating film; and

transmitting means mounted on said other end of said cantilever for transmitting a mechanical vibration from said stylus to respective pairs of said piezo-resistive elements to change the tension on said piezo-resistive elements and the electrical resistance properties thereof as a function of the transmitted mechanical vibration.

2. A pick-up cartridge as defined in claim 1, wherein said transmitting means comprises a member fixed to said cantilever and having four projections radially extending therefrom, adjacent projections being at right angles to each other, in a plane substantially perpendicular to the longitudinal axis of said cantilever.

3. A pickup cartridge, comprising:

a cantilever;

a stylus mounted at one end of said cantilever;

a support member supporting said cantilever at its other end;

first and second flexible insulating film bases connected to said support member;

first and second band-shaped semiconductor piezo-resistive elements, each having electrodes at its opposite ends, parallelly disposed on and supported by said first and second film bases, respectively; and

transmitting means mounted on said other end of said cantilever for transmitting a mechanical vibration from said stylus to said piezo-resistive elements, said transmitting means comprising a member having first and second projections extending radially therefrom substantially at right angles to each other and in a plane substantially perpendicular to the longitudinal axis of said cantilever, said transmitting means changing the tension on said piezo-resistive elements and the electrical resistance properties thereof as a function of the transmitted mechanical vibration.

4. A pick-up cartridge, comprising:

a cantilever;

a stylus mounted on one end of said cantilever;

a support member supporting said cantilever at its other end;

a substantially square-shaped flexible insulating film base,

having a central opening and first and second bandshaped portions defined between the sides of said insulating film base and said central opening, connected to said support member;

first and second band-shaped semiconductor piezo-resistive elements, each having electrodes at its opposite ends and mounted substantially perpendicular to each other on said first and second band-shaped portions of said insulating film, respectively; and

transmitting means mounted on said other end of said cantilever for transmitting a mechanical vibration from said stylus to said piezo-resistive elements to change the tension on said piezo-resistive elements and the electrical resistance properties thereof as a function of the transmitted mechanical vibration.

5. A pick-up cartridge as defined in claim 4, wherein said transmitting means comprises a member fixed to said cantilever having four arms extending radially therefrom adjacent arms being substantially perpendicular to each other and in a plane substantially perpendicular to the longitudinal axis of said cantilever.

stylus to said piezo-resistive elements to change the tension on said piezo-resistive elements and the electrical resistance properties thereof independently of each other as a function of the transmitted mechanical vibration.

7. A pick-up cartridge as defined in claim 6, wherein said transmitting means comprises a member having first and second projections radially extending therefrom substantially at right angles to each other and in a plane substantially perpendicular to the longitudinal axis of said cantilever.

8. A pick-up cartridge, comprising:

a cantilever;

a stylus mounted on one end of said cantilever;

a support member supporting said cantilever at its other end;

first and second flexible insulating film bases mounted on said support member in a cross-shaped form;

at least two band-shaped semiconductor piezo-resistive elements, each having electrodes at its opposite ends, said piezo-resistive elements being disposed on at least one of two arms of each of said insulating film bases; and

transmitting means mounted on said other end of said cantilever for transmitting a mechanical vibration from said stylus to said piezo-resistive elements to change the tension on said piezo-resistive elements and the electrical resistance properties thereof as a function of the transmitted mechanical vibration.

9. A pick-up cartridge as defined in claim 8, wherein said transmitting means comprises a circular pressure applying member having a cylindrical abutment and disposed in a plane substantially perpendicular to the longitudinal axis of said cantilever. 

1. A pick-up cartridge, comprising: a cantilever; a stylus mounted on one end of said cantilever; a support member supporting said cantilever at its other end; a substantially square-shaped flexible insulating film base, having a central opening and four band-shaped portions defined between the sides of said insulating film and said central opening, connected to said support member; four band-shaped semiconductor piezo-resistive elements, each having electrodes at its opposite ends and mounted respectively on said four band-shaped portions of said insulating film; and transmitting means mounted on said other end of said cantilever for transmitting a mechanical vibration from said stylus to respective pairs of said piezo-resistive elements to change the tension on said piezo-resistive elements and the electrical resistance properties thereof as a function of the transmitted mechanical vibration.
 2. A pick-up cartridge as defined in claim 1, wherein said transmitting means comprises a member fixed to said cantilever and having four projections radially extending therefrom, adjacent projections being at right angles to each other, in a plane substantially perpendicular to the longitudinal axis of said cantilever.
 3. A pick-up cartridge, comprising: a cantilever; a stylus mounted at one end of said cantilever; a support member supporting said cantilever at its other end; first and second flexible insulating film bases connected to said support member; first and second band-shaped semiconductor piezo-resistive elements, each having electrodes at its opposite ends, parallelly disposed on and supported by said first and second film bases, respectively; and transmitting means mounted on said other end of said cantilever for transmitting a mechanical vibration from said stylus to said piezo-resistive elements, said transmitting means comprising a member having first and second projections extending radially therefrom substantially at right angles to each other and in a plane substantially perpendicular to the longitudinal axis of said cantilever, said transmitting means changing the tension on said piezo-resistive elements and the electrical resistance properties thereof as a function of the transmitted mechanical vibration.
 4. A pick-up cartridge, comprising: a cantilever; a stylus mounted on one end of said cantilever; a support member supporting said cantilever at its other end; a substantially square-shaped flexible insulating film base, having a central opening and first and second band-shaped portions defined between the sides of said insulating film base and said central opening, connected to said support member; first and second band-shaped semiconductor piezo-resistive elements, each having electrodes at its opposite ends and mounted substantially perpendicular to each other on said first and second band-shaped portions of said insulating film, respectively; and transmitting means mounted on said other end of said cantilever for transmitting a mechanical vibration from said stylus to said piezo-resistive elements to change the tension on said piezo-resistive elements and the electrical resistance properties thereof as a function of the transmitted mechanical vibration.
 5. A pick-up cartridge as defined in claim 4, wherein said transmitting means comprises a member fixed to said cantilever having four arms extending radially therefrom adjacent arms being substantially perpendicular to each other and in a plane substantially perpendicular to the longitudinal axis of said cantilever.
 6. A pick-up cartridge, comprising: a cantilever; a stylus mounted on one end of said cantilever; a support member supporting said cantilever at its other end, said support member having first and second strips radially extending therefrom in a V-shaped configuration; a flexible insulating film base mounted on said support member; first and second band-shaped semiconductor piezo-resistive elements, each having electrodes at its opposite ends, disposed on said first and second strips, respectively; and transmitting means mounted on said other end of said cantilever for transmitting a mechanical vibration from said stylus to said piezo-resistive elements to change the tension on said piezo-resistive elements and the electrical resistance properties thereof independently of each other as a function of the transmitted mechanical vibration.
 7. A pick-up cartridge as defined in claim 6, wherein said transmitting means comprises a member having first and second projections radially extending therefrom substantially at right angles to each other and in a plane substantially perpendicular to the longitudinal axis of said cantilever.
 8. A pick-up cartridge, comprising: a cantilever; a stylus mounted on one end of said cantilever; a support member supporting said cantilever at its other end; first and second flexible insulating film bases mounted on said support member in a cross-shaped form; at least two band-shaped semiconductor piezo-resistive elements, each having electrodes at its opposite ends, said piezo-resistive elements being disposed on at least one of two arms of each of said insulating film bases; and transmitting means mounted on said other end of said cantilever for transmitting a mechanical vibration from said stylus to said piezo-resistive elements to change the tension on said piezo-resistive elements and the electrical resistance properties thereof as a function of the transmitted mechanical vibration.
 9. A pick-up cartridge as defined in claim 8, wherein said transmitting means comprises a circular pressure applying member having a cylindrical abutment and disposed in a plane substantially perpendicular to the longitudinal axis of said cantilever. 